Advanced Materials Research Vols. 150-151

Abstract: In this paper, asphalt and asphalt mortar are aged in different periods of time by pressure aging vessel (PAV). Systematic tests are made on aged asphalt and asphalt mortar of different aging levels to gain performance indexes such as dynamic shear modulus, phase angle, bending creep stiffness under low temperature, bending creep rate under low temperature, direct tension tensile strength and direct tension failure strain. These indexes are then used to analyze the relationship and regularity between asphalt mortar’ test indexes and high temperature stability, fatigue resistance and anti-cracking performance under low temperature. The test results show that asphalt mortar’ high temperature stability is strengthened as the aging time is prolonged, that the asphalt mortar’ fatigue resistance is reduced when the temperature drops, and that anti-cracking performance under low temperature is weakened when the aging time is extended. In addition, cracking under low temperature was more liable to occur when fine ores are added. As the brittle point tends to increase when the temperature gets lower, cracking is more likely to occur on the asphalt mortar.

Abstract: Effect of thermal treatments on the structural and electrical properties of the chemical bath deposition derived Ti-doped ZnO thin films are studied. XRD results show that the annealed Ti-doped ZnO films with wurtzite structure are randomly oriented. Crystallite structure, carrier concentration, resistivity and mobility are found to be dependent on the treatment temperature. At a treatment temperature of 100°C, the Ti-doped ZnO film possesses a carrier concentration of 1.3×1020 cm-3, a resistivity of 3×10-3 Ω-cm, and a mobility of 15 cm2/Vs.

Abstract: Room-temperature electrical conductivity property of Si3N4/TiN composite ceramics fabricated by Si3N4 powders from iron ore tailing and high titanium slag was investigated. Si3N4/TiN composite ceramics were machined by electrical discharge machining. The results show that the minimum amount of TiO2 in initial raw materials is about 20wt% for the formation of electroconductive network in the composites, of which the electric resistivity is 4.25×10-2•cm. The electric resistivity decreases slightly with increasing the sintering temperature. Surface roughness enhances significantly with the speed of the electrical discharge machining rising.

Abstract: In order to defer early damages of asphalt pavement, a new regeneration and restoration technology of asphalt pavement surface is presented in preventive maintenance. The regeneration mechanism and the restoration mechanism were analyzed and the applicable conditions of the technology were proposed. Based on the application of tested road, the relevant construction technology and requirements were put forward. The results show that the new regeneration and restoration technology can better restore the surface performances of original asphalt pavement and prolong the service life of asphalt pavement；in contrast with the traditional preventive maintenance technology, it has a good economic benefit, which is worthy of making more widespread popularization and application in preventive maintenance of asphalt pavement.

Abstract: Green roof systems are living vegetation integrated on top of roofs. They could enhance the built environment in a number of ways. Herein, different types of green roof and their structural arrangement and materials design are introduced. Various benefits offered by green roof to the urban habitat are discussed. Finally, examples of applications of green roofs are presented.

Abstract: The effect of different electric pulse parameters which include capacitance, voltage, frequency and treating time on the hot galvanizing coatings was studied through orthogonal test of array L25. For each factor, five levels were chosen to cover the experimental region. Results showed that the thicknesses of ally layer with different parameter were all reduced. It is from 63.57μm to 28.49μm. The intuition analysis of orthogonal test derived that the pulse capacitance had the most significant influence on the growth of alloy layer, and the influence of other factors was little. The optimum parameter combination were the capacitance of 200μF , the voltage of 700V, the pulse frequency of 4 Hz, and the treating time of 30 s.

Abstract: When conducting nonlinear analysis of frame structure, we usually adopt plastic hinge model or plastic zone model which based on bending beam theory. But the effect of shear deformation on element deformation are not considered in the analysis model established based on bending beam theory, which is only applicable to the elements with large span depth ratio. For the main structure of steel mega-frame structures, the depth of element section is very high. Thus it can not meet bending beam theory assumption. The common analysis model can not simulate structure reaction accurately. This article puts forward some treatment methods for existing problems of nonlinear analysis of steel mega-frame structures, establish member element stiffness matrix based on improved finite segment element plastic zone model and consider the effect of element shear deformation on plastic development.

Abstract: Asbestos-free frictional material is developed by using phenol formaldehyde resins modified with nano- SiO2 as matrix while surface-treated sisal fiber and glass fiber are used as reinforcement. The friction and wear properties were investigated on Constant speed (D-SM) tester. The abrasion surfaces of composites were observed by scanning electron microscope (SEM). Test result shows that all the properties, such as, friction coefficient and wear can meet the GB5763-2008 requirement. When the sisal fiber and glass fiber hybrid ratio is 2:1, the composite has the high mechanical property, suitable and stable coefficient of friction and relatively low wearability especially at high temperature.

Abstract: Proper estimate of autogenous shrinkage of self-consolidating concrete (SCC) can provide engineers with the information necessary for producing high quality products manufactured with SCC. An experimental program was undertaken to evaluate autogenous shrinkage of precast, prestressed SCC. Sixteen SCC with slump flow of 680 ± 20 mm were evaluated. These mixtures were made with 440 to 500 kg/m3 of binder, Type MS cement or HE cement and 20% Class F fly ash, 0.34 to 0.40 w/cm, viscosity-modifying admixture content of 0 to 100 mL/100 kg of binder, and 0.46 to 0.54 sand-to-total aggregate volume ratio. Two high-performance concretes (HPC) with 0.34 and 0.38 w/cm and slump of 150 mm were also investigated. HPC developed similar autogenous shrinkage at 56 days compared to SCC made of a given binder type. Shrinkage was compared to prediction models proposed by Tawaza and Miyazawa 1997, Jonasson and Hedlund 2000, and CEB-FIP 1999. The Tazawa and Miyazawa model was modified to provide adequate prediction of autogenous shrinkage for precast, prestressed SCC.

Abstract: Ni-Cu-Zn ferrite/CaTiO3 and Ni-Cu-Zn ferrite/BaTiO3 composites which can be applied in low temperature co-fired ceramic (LTCC) technology were synthesized by conventional solid-state reaction lower than 950°C. The complex permeability spectra of the above two composites have been investigated. The contribution of spin rotation and domain wall motion to the permeability spectra was estimated by the numerical fitting of measured data to the relevant formula. Influence of two types of magnetizing processes on the permeability of different composites has been analyzed combining with the variation of microstructures.